[swift-users] another issue with tuples

Shane S electro_alchemy at hotmail.com
Wed Jul 6 08:55:32 CDT 2016

Aaron this works for me in both Swift 2.2 and Swift 3 provided that you remove the ‘throws’ keyword.

What seems odd to me is not the first assignment, but rather the second that _allows_ the use of ‘throws’ when t.1 (i.e. f) does not throw - is your concern the same?


On Jul 5, 2016, at 10:48 PM, Aaron Bohannon via swift-users <swift-users at swift.org<mailto:swift-users at swift.org>> wrote:

Yesterday, it was pointed out that a variable name referring to a tuple cannot be used as a pattern.  I have noticed another sort of inconsistency in how tuples are treated when they are referenced by name:

func f() -> Int { return 5 }

let t = ("a", f)

let _: (String, () throws -> Int) = t  // type error
let _: (String, () throws -> Int) = (t.0, t.1)  // OK

This situation leads to a different sort of type error; however, the error seems equally unwarranted.  I can't see any good reason for a well-typed program to become ill-typed when `(t.0, t.1)` is replaced with `t` (assuming `t` is a pair).

Should I file a separate bug for the specific example above?

- Aaron
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